Intermediate Visual Acuity of Presbyopic Individuals with and without Distance and Bifocal Lens Corrections.

摘要

Visual acuity was determined at the intermediate range for older individuals with various combinations of ocular refractive error (nine subcategories) and accommodative power (three subcategories). Subjects (N=249) read numerals ranging in size to measure visual acuity from 20/80 to 20/15 at 51, 76, and 102 cm (20, 30, and 40 in) with 50 fL luminance. Monocular visual acuity scores were determined both with the subject's optimum spectacle lens correction for distance vision (6 m, 20 ft) and near vision (0.4 m, 16 in) and without lenses. For subjects with low accommodative power, neither the distance nor the near lens correction provides normal vision throughout the intermediate range. At 102 cm vision is better with the distance correction, while at 51 cm visions is better with the near correction. At 76 cm neither lens offers normal vision.